Background: This study implemented an external quality assessment (EQA) of serum protein electrophoresis (SPEP) and immunofixation electrophoresis/immunotyping (IFE/IT) tests and aimed to present domestic guidelines regarding the interpretation report.
Methods: We conducted the EQA of SPEP and IFE/IT tests similar to the proficiency testing (PT) program of the Korean Association of External Quality Assessment (KEQAS). We prepared four test samples by pooling residual serum specimens, according to the SPEP pattern, and the existence and isotype of monoclonal proteins. Each test sample was aliquoted and sent to 29 clinical laboratories, each laboratory conducted SPEP and IFE/IT tests and returned quantitative values and interpretation reports.
Results: Variations in the quantitative values (g/dL) of each fraction and ratios (%) of each fraction to total protein were observed. The differences between the electrophoresis methods or manufacturers were not statistically significant. Of the four EQA samples, two samples had a monoclonal protein, and the presence and absence of monoclonal protein and isotypes were consistent in all participating institutions. However, there were statistically significant differences in the numerical values and ratios of monoclonal proteins between institutions.
Conclusions: This study examined the possibility of SPEP and IFE/IT tests being included in the PT program of the KEQAS, and we identified what should be supplemented for future assessments. Furthermore, we have presented the guidelines regarding SPEP and IFE/IT tests in Korea for the first time, and further studies are required to establish the EQA programs and standardized guidelines.

Keywords: Serum protein electrophoresis, Immunofixation electrophoresis, Immunotyping, External quality assessment, Proficiency testing program, Korean Association of External Quality Assessment